The theft of electronic devices is on the rise because of the convenient size of the devices and the high monetary return a thief can receive for stolen devices. One such electronic device is a selective call receiver. Many electronic devices have a variety of options, some or all of which can be activated upon purchase. For individualization of a device, it is desirable that a user be able to alter some or all of the device's optional features. These options are typically stored in an electrical erasable, programmable read only memory (EEPROM), but can be stored in other programmable nonvolatile memory devices. Allowing the user the ability of reprogramming some or all of the options, however, also allows a thief to reprogram these options unless the electronic device is protected against unauthorized reprogramming.
Each selective call receiver has a unique selective call address that allows for the receiver to receive selective call messages so addressed. The selective call address is typically stored in an EEPROM called a code plug. Other selective call receiver options are customarily established by other information stored in the code plug. Regrettably, allowing code plug reprogrammability to the user also allows for possible reprogramming of the EEPROM unauthorized by the user.
Generally, stolen selective call receivers are useless unless the selective call address can be changed. If the selective call address remains unchanged, the new user of the selective call receiver could only receive messages intended for the previous owner. In various selective call receivers manufactured today, the frequency that the receiver operates on can be altered by reprogramming the code plug. Altering the frequency would allow the selective call receiver to operate within another selective call system making the purchase of the stolen selective call receiver more desirable. Also, the purchase of a stolen electronic device would be less desirable if the user could not take advantage of all of the options for which the device was designed.
Thus, what is needed is a method and apparatus for protected reprogrammability of an electronic device.